Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
  • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
  • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B17/00—Chain saws; Equipment therefor
  • B27B17/14—Arrangements for stretching the chain saw
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/305—Directional control characterised by the type of valves
  • F15B2211/30505—Non-return valves, i.e. check valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/40—Flow control
  • F15B2211/405—Flow control characterised by the type of flow control means or valve
  • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/40—Flow control
  • F15B2211/42—Flow control characterised by the type of actuation
  • F15B2211/428—Flow control characterised by the type of actuation actuated by fluid pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/40—Flow control
  • F15B2211/46—Control of flow in the return line, i.e. meter-out control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/40—Flow control
  • F15B2211/47—Flow control in one direction only
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
  • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
  • F15B2211/7051—Linear output members
  • F15B2211/7053—Double-acting output members
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
  • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
  • F15B2211/72—Output members, e.g. hydraulic motors or cylinders or control therefor having locking means
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T83/00—Cutting
  • Y10T83/707—By endless band or chain knife
  • Y10T83/7226—With means to guard the tension
  • Y10T83/7239—With means to vary distance between pulley or sprocket axes
  • Y10T83/7251—Including means to yieldably bias pulley
  • Y10T83/7258—By fluid means

Definitions

• the present invention concerns a valve arrangement for adjusting a hydraulic saw chain tightening device in sawing gear that includes a holder and a saw bar displaceable in a longitudinal direction relative to the holder for regulating the tightness of a saw chain running around the saw bar and holder, whereby the s$w chain tightening device is connected by the valve arrangement to a hydraulic circuit system and includes at least one hydraulic piston affecting the saw bar.
• a timber cutting unit comprising a sawing gear that includes a saw chain and a saw bar.
• Efficient logging puts high demands on the equipment used with regard to safety, robustness, ease-of-use as well as precision and performance, ie. that the equipment works quickly.
• the attachment includes plate with a grooved recess in which a steering part united with the saw bar moves in the saw bar's longitudinal direction.
• a piston projecting from the recess in the plate in the longitudinal direction of the saw bar bears on the guiding part when in its active operating position.
• the piston get its power from a fluid system integrated and enclosed in the plate and that includes a gas-sprung pressure chamber that is connected to the piston by a line and a valve.
• the valve is a manually switchable check valve, that in one position permits fluid to flow only from the pressure chamber to the piston, thus tightening the chain by displacing the saw bar, and in a second position permits fluid to flow only from the piston to the pressure chamber, which, due to an increase of pressure in the chamber, restores the position of the piston when, for example, replacing the saw chain with a new one.
• the technology of an enclosed system carries with it, among other things, the limitation that the pressure at the piston varies depending on the position of the piston. Tbe stretching force is greater when the piston is in its inner position and somewhat less when the piston is in its outer position. Further disadvantages are the problems of having to maintain and/or consciously be able to vary the pressure and thus the stretching force over time.
• the check valve is switched and a levering tool is ujsed to force back the piston-
• SE 502,386 illustrates how a similar piston is arranged, in this case in a steering pant permanently attached to the saw bar and accommodated in a groove in the attachment/holder, whereby the piston, when affected by the fluid under pressure, keeps the saw bar in a position displaced from the attachment/holder.
• the piston receives its power from a hydraulic system on the mechanical equipment on which the sawing gear is mounted.
• An additional pair of pistons are also found on the same hydraulic system arranged to stabilise the saw bar by means of a clamping action across the direction of displacement of the saw bar.
• the saw bar is thus affected partly by a piston arranged to push the blade --com the holder so that the saw chain is kept tight, and partly by at least one damping piston that holds the blade tightly and stabilises it in position.
• the force keeping the chain tight is somewhat greater than the force of friction that results from the clamping pistons so that a continuous tightening is achieved while the chain still displays a relatively stable attachment
• All the pistons are connected to the machinery's hydraulic system and when this equipment is in operation, the pistons are provided with what is essentially a constant pressure.
• a check valve is also arranged in the line from the hydraulic system. This check vaive is essential to ensure that the saw chain does not become slack during operation. This could (happen as a result of the rapid loading and pressure increases that occur at the piston, for example, at start-up when ihe saw chain goes from stationary position to full speed in a very short rime, or when a saw chain moving at high speed is forced against a tree trunk or when a branch gets caught in the chain, etc.
• One object of the present invention is to overcome the disadvantages mentioned above and to achieve a valve device that functions as a check valve when the hydraulic system is pressurised, and that automatically evacuates the pressure without fluid spillage when the hydraulic system is not pressurised, thereby making it possible to replace a saw chain without the need for any . special tool.
• valve device of a -rind first mentioned above and which has those features evident from the characteristics of attached claim 1.
• a valve device that, when the equipment is in operation and the hydraulic system pressurised, is by means of this pressure in a condition that renders it able -co function as a cheek valve that allows the fluid to flow in a direction towards the pisto ⁇ (s), and, when the equipment is shut down and the hydraulic system is accordingly unpressurised, is by means of the absence of this pressure, in a condition that allows the fluid to flow back from the piston(s).
• Fig. 1 shows schematically a sawing gear with constituent parts.
• Fig.2 shows the arrangement of a hydraulic coupling according to one embodiment of the present invention.
• Figs.3 and 4 show a section of the holder according to Fig. 1 including a valve device according to one embodiment of the present invention in its working position and resting position respectively.
• Fig. 5 shows a check valve device according to one embodiment of the present invention.
• Figs.6 and 7 show a section of the holder according to Fig. 1 including a valve device according to an alternative embodiment of the present invention in its working position and resting position respectively.
• valve device can either be arranged in its own stand-alone valve housing or it can be wholly or partially integrated in another component of the hydraulic system or sawing gear to which the valve device is connected.
• the valve device is integrated in a holder for the displaceable saw bar that is included in the sawing gear.
• Fig. 1 is a schematic illustration of sawing gear containing a holder 1, from which extend two parallel forks.
• the forks delineate a groove or a space between them intended to be taken up by a steering component 4 permanently attached to the saw bar 2.
• the steering component 4 has an essentially T-shaped cross-sectional pro ile and, together with the saw bar, forms what is essentially an H-shaped end piece whose narrow middle section is intended to occupy the grobve between the forks. This accomplishes a connection of the saw bar to the holder that is displaceable in the direction of travel of the saw bar. The displacement thus allows the tightness of a saw chain 3 running around the saw bar to be adjusted.
• the chain stretching device includes a hydraulic piston S arranged in the holder 1 and active in the direction of the displacement of the saw bar.
• This hydraulic piston is referred to below as the tightening piston.
• the tightening piston 5 is arranged in the groove and applies a force against the saw bar's steering component 4 when the tightening piston is subjected to hydraulic pressure, at which it has the effect of displacing the saw bar in the direction away from the holder, where, in fact, the driving wheel of the saw chain is arranged.
• the tightening piston receives its pressure setting from the hydraulic system, by which a continuous and even stretching of the saw chain is accomplished.
• Our valve device 6 is arranged connected to the tightening piston 5 and, in the present embodiment, includes a cylindrical space 7 and a displaceable piston device 8 that is adapted to fit and move in the space, see figs. 3 and 4.
• Space 7 has openings in front of piston device 8; one is for the connection line 9 of the hydraulic system, referred to below as the inlet, and another is the connection 10 to the tightening piston 5, referred to below as the outlet.
• Outlet 10 is arranged with a check valve function, for example, in the form of a flap 11 that is moveable between an open position (see tig: 4) that allows hydraulic fluid to flow freely between the outlet and the inlet 9, and an active check valve position (see fig. 3) that allows hydraulic fluid to flow in the direction from inlet 9 through outlet 10 to apply pressure to the chamber 5' behind the tightening piston 5 but which prevents liquid flow in the opposite direction.
• a check valve function for example, in the form of a flap 11 that is moveable between an open position (see tig: 4) that allows hydraulic fluid to flow freely between the outlet and the inlet 9, and an active check valve position (see fig. 3) that allows hydraulic fluid to flow in the direction from inlet 9 through outlet 10 to apply pressure to the chamber 5' behind the tightening piston 5 but which prevents liquid flow in the opposite direction.
• piston device 8 In the space, piston device 8 is under tension from a spring in the direction towards the openings and has an extended projection 12 in the forward direction.
• the flap device 11 comes under the influence of the extended projection 12iof the sprung piston, by which the projection 12 causes the flap to take up its open position.
• the hydraulic system is de-pressurised by, for example, switching off the machine that powers the hydraulic system and that may also support the sawing gear.
• the pressure in chamber 7 Calls and eventually reaches a level that can be overcome by the pro-sprung piston device, whose extended projection 12 then applies a force to flap 11 that opens the check valve so that the pressure behind outlet 10 is released when the fluid is once again allowed t o flow back through the outlet and into chamber 7.
• the saw bar can be pressed back into t he bolder by hand and a new chain fitted or an old one removed without the need for any great exertion or special tools.
• the holder also includes clamping piston devices 13 arranged across the direction of travel of the saw bar and that are also connected to a hydraulic system, preferably the same hydraulic system as the tightening piston.
• the clamping piston devices 13 must also be released when the saw chain is to be replaced. It is thus advantageous if even these can be equipped with a valve device according to the present invention, which in the present embodiment is preferably connected t o the same valve device as the tightening piston. This can be achieved, for example, by channels in the holder between the different pistons 5 and 13.
• the system can be balanced, for example, by means of flow reducing restrictions in the different lines that connect the pistons.
• a predetermined flow restriction in the flow channel connections to clamping pistons 13 can be accomplished by the tightening piston 5 tightening the saw chain before the hydraulic pressure presses the clamp pistons 13 to its full extent.
• space 7 consists of a hole bored in holder 1.
• the hole is threaded to a p ⁇ e-dete ⁇ nined depth so that a screw or plug can be used to close-off the hole.
• Piston device 8 displays a cylindrical part that is adapted to the side walls of the hole. To ensure the tightness between the piston and the wall, at least one groove is also arranged around the piston's cylindrical section for a seal, e.g. an O-ring or piston ring or similar.
• the said projection 12 for opening the check valve is located at the front of the piston device. This projection should be designed so that it does not hinder the fluid from flowing past when it projects forward and opens the check valve.
• the projection 12 should, therefore, have a cros ⁇ - section that is significantly less than the diameter of the hole and that is less than, or at least equal t o, the opening it creates by opening the check valve.
• a spring of suitable type e.g. a spiral spring, is inserted before the screw is threaded into the hole to close off the valve device.
• the flap device 11 contains a plate-like flap 21 that moves between two stop positions 22 and 23.
• flap 2 bears on and seals off the flow path from outlet 10 to space 7.
• the flap bears on outlet path 23 during the build-up of open passages for the flow through of fluid.
• These openings, through which fluid can flow in the second position can, for example, be made in the actual flap to the side of that part of the flap surface thai closes off the flowpath, or the flap's forward limitations 23 can be made shoulder-like to leave a gap between where the fluid can flow when the flap lies against them, or by some other solution applicable for the flaps.
• the flap device can also contain a flap that is arranged to swing at a wall in outlet 10.
• the flap device can be arranged with a light spring that ensures that the flap takes up a check valve location bearing on stop position 22 when not under the influence of an external pressure.
• the said cylindrical space 7 and the pist ⁇ n device 8 that is accordingly designed to fit and move in that space do not necessarily need to have a circular cross-section, but can have other shapes that are also suitable for the current application, such as oval, rectangular, etc.
• the piston device's adjustment of the returning fluid can be arranged in another manner.
• a return flow passage 31 has been arranged from a location behind the check valve, which here can be a y check valve known to a specialised skilled person, to the cylindrically shaped space.
• the return flow passage opens into the cylindrically shaped space in a position that, with the piston device in its rear location (see fig.

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Publications (2)

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Cited By (4)

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Citations (3)

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• 1997
  • 1997-02-06 SE SE9700413A patent/SE512961C2/sv not_active IP Right Cessation
• 1998
  • 1998-02-03 US US09/355,884 patent/US6311599B1/en not_active Expired - Lifetime
  • 1998-02-03 WO PCT/SE1998/000195 patent/WO1998034768A1/en active IP Right Grant
  • 1998-02-03 BR BR9807664-7A patent/BR9807664A/pt active Search and Examination
  • 1998-02-03 CA CA002278733A patent/CA2278733A1/en not_active Abandoned
  • 1998-02-03 AU AU60103/98A patent/AU730397B2/en not_active Expired
• 1999
  • 1999-07-29 NO NO19993705A patent/NO311790B1/no not_active IP Right Cessation
  • 1999-08-02 FI FI991664A patent/FI122020B/sv not_active IP Right Cessation

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